1. Field of the Invention
The present invention relates to a marine propulsion system. More specifically, the present invention relates to a marine propulsion system including an engine.
2. Description of the Related Art
Conventionally, marine propulsion units (marine propulsion systems) including an engine are known in the art (for example, see JP-A-Hei 9-263294). JP-A-Hei 9-263294 discloses a marine propulsion unit including an engine and a power transmission mechanism transmitting a driving force of the engine to a propeller in a certain fixed reduction ratio. The marine propulsion unit is constructed such that the driving force of the engine is directly transmitted to the propeller via the power transmission mechanism and the rotational speed of the propeller increases proportionally with an increase in the engine speed.
However, the marine propulsion unit disclosed in JP-A-Hei 9-263294 has a problem in which it is difficult to improve acceleration performance in a low speed position when the speed reduction ratio of the power transmission mechanism is set to achieve a larger maximum speed. Conversely, there is a problem that it is difficult to achieve a larger maximum speed when the reduction ratio of the power transmission mechanism is set to improve the acceleration performance in the low speed position. In other words, the marine propulsion unit disclosed in JP-A-Hei 9-263294 has a problem in which it is difficult for the user to achieve both an acceleration performance and a maximum speed approaching the levels that he/she desires.